Inhibitory effects against SARS-COV-2 main protease of terpenic substances and selenated naphthoquinones

Clinical studies on COVID-19 patients revealed among multiple symptoms, uncontrolled production of inflammatory mediators. The current study presents the inhibitory effects of eleven terpenoid derivatives (<b>1–11</b>) and two naphthoquinones (<b>12</b> and <b>13</b>) on the main protease (Mpro) of SARS-CoV-2. All the terpenoids and compound <b>13</b> displayed weak inhibitory effects while compound <b>12</b> showed moderate inhibitory effects of M^pro with IC₅₀ of 50.2 µM. Anti-inflammatory effects against pro-inflammatory mediators produced in LPS-induced lung injury and the cytotoxicity against Vero and THP-1 cell lines of molecules <b>12</b> and <b>13</b> were also evaluated. Molecules <b>12</b> and <b>13</b> presented promising anti-inflammatory activity by attenuating the exudation and neutrophil and leukocyte migration.